1. Field of the Invention
The present invention concerns improvements relating to electronic key readers.
2. Description of Background and Relevant Information
In the field of access controls, each authorized user has a badge provided with an electronic device which, once fed by an outside source, emits a coded signal allowing a door to open, for instance, when it is recognized by the reader.
The reader transmits the energy necessary to the functioning of the badge by a self-inductance coupling, which means that the reader and the badge both comprise an antenna that is in the form of a coil.
The reader is arranged on the exterior of the premises to which one controls access, and means preventing acts of vandalism need to be provided. Generally, the reader is enclosed in a very resistant metal housing that is solidly fixed to the frontage. The outer surface of this housing has slots to allow the flux from the antenna to radiate outward. In some cases, the reader is embedded and its front surface is protected by a metal plate.
Experiments have shown that, to be efficient, the badge should be placed relatively close to the reader, which is explained in that the metal housing, or the plate, acts like a turn that is traversed by the flux emitted by the antenna which absorbs part of the energy emitted by the latter by transforming it into heat.
The present invention, which overcomes this drawback, is remarkable in that the housing has a slot extending from one of the edges of the housing substantially to the center of the front surface of the latter.
An electronic key reader includes a protective metal housing member comprising a front surface having a center and edges. At least one slot extends from at least one of the edges to the center of the front surface.
The protective metal housing may have the form of a plate, the at least one slot may comprise an open end and one end that extends beyond a median line connecting sides which are adjacent to a side that includes the open end. The at least one slot may comprise an open end that is arranged at one of the edges. The front surface may be four-sided and the at least one slot may open out at the at least one of the edges. The front surface may be polygonal and the at least one slot may open out at the at least one of the edges.
The key reader may further comprise an antenna loop arranged to surround a center region of the front surface. The key reader may further comprise an antenna loop, wherein the at least one slot traverses the antenna loop. The key reader may further comprise openings arranged on the protective metal housing.
The at least one slot may comprise a first slot and a second slot, the first slot extending from one edge and the second slot extending from a different edge. The key reader may further comprise a plurality of lateral surfaces. The at least one slot may extend into at least one of the plurality of lateral surfaces.
The invention also provides for an electronic key reader comprising a protective metal plate comprising a front surface, a center region, and edges. The protective metal plate comprises at least one slot extending from at least one the edges to the center region.
The at least one slot comprises an open end that is arranged at one of the edges. The protective metal plate may be four-sided and wherein the at least one slot opens at the at least one of the edges. The protective metal plate may be polygonal and wherein the at least one slot opens at the at least one of the edges.
The key reader may further comprise an antenna loop arranged to surround the center region of the front surface. The key reader may further comprise an antenna loop, wherein the at least one slot traverses the antenna loop. The key reader may further comprise corner openings arranged on the protective metal plate. The at least one slot may comprise a first slot and a second slot, the first slot extending from one edge and the second slot extending from a different edge. The key reader may further comprise a plurality of lateral surfaces. The at least one slot may extend into at least one of the plurality of lateral surfaces.
The invention also provides for an electronic key reader comprising a member comprising one of a protective metal plate and a protective metal housing. The member comprises a front surface, at least one edge, and at least two opposite sides. At least one slot comprises an open end and a closed end, the at least one slot having a length which is defined between the open and closed ends. The length is equal to or greater than a length of the two opposite sides.
The member may be four-sided. The member may be polygonal. The key reader may further comprise an antenna loop arranged to surround a center region of the front surface. The key reader may further comprise an antenna loop, wherein the at least one slot traverses the antenna loop. The key reader may further comprise corner openings. The at least one slot may comprise a first slot and a second slot, the first slot extending from one edge and the second slot extending from a different edge. The key reader may further comprise a plurality of lateral surfaces. The at least one slot may extend into at least one of the plurality of lateral surfaces.